Well, I mean, it's part of the superhumanness of game characters. I mean, Zell punches out dolphins and meteors, and things like that.
Also, there's magic involved, I mean your character, Duncan, super hastes himself and FVGT's Ein freezes time. I don't see why being able to make machines from pieces of scrap metal and metal his collected in seconds be more far-fetched than those limit breaks.

Edit:
Shiinen are you referring to your character Eika not being able to use a vending machine?
If so, perhaps Xerox can create an automatic guidance manual gun for her! Turn it on, aim and shoot! Tadah! The gun will then start telling you how to use any device!
(By the way, if I am still on, every minute from now on, anything I post will probably get more crazy than the last somehow)